Photoprotection of Wood Surfaces by Wood-Ion Complexes
Keywords:
Weathering, ferric chloride, chromium trioxide, infrared and ultraviolet spectrophotometers, nuclear magnetic resonanceAbstract
Mechanisms for protection of wood surfaces against weathering imparted by metal ions of inorganic salts, namely ferric ions and chromium ions, were elucidated. The lignin model compounds study revealed that the effectiveness of weathering protection is likely due to formation of complex between wood components and ferric chloride as well as chromium trioxide, which induced energy transfer to provide protection. The complex formation between lignin model compounds and metal ions was confirmed by the analyses of their infrared spectra, ultraviolet-visible spectra, and nuclear magnetic resonance spectra. These findings revealed that guaiacol and catechol reacted with metal ions to form water-insoluble complexes. Although cellobiose-ion complex was not isolated, it was evident by IR study that cellobiose participated in complex formation and accelerated the rate of complex formation. Like model compounds, it is plausible that wood-ion complexes being formed at the wood surfaces effectively blocked the free phenolic hydroxy groups, which are the reactive centers to initiate photochemical reactions, and thereby provided photoresistance to wood surfaces. It is likely that the complex systems are capable of minimizing photochemical reactions by energy transfer from wood to wood complexes, to emit effective energy harmlessly from wood surfaces. In addition, it is possible that wood-ion complexes might decompose peroxide impurities formed at wood surfaces to avoid photodegradation chain reactions.References
Black, J. M., and E. A. Marz. 1974. Inorganic surface treatments for weather-resistant natural finishes. USDA For. Serv. Res. Pap., FPL-232, For. Prod. Lab., Madison, WI.nChang, S.-T., D. N.-S. Hon, and W. C. Feist. 1982. Photodegradation and photoprotection of wood surface. Wood Fiber14(2):104-117.nDolenko, A. J., and R. L. Desai. 1977. Exterior durability of some eastern Canadian wood species treated with zinc salts. J. Coat. Technol.49(635):79-86.nFeist, W. C. 1978a. Proc. of Symp. on Structural Use of Wood in Adverse Environments, Soc. of Wood Sci. and Technol. Vancouver, B.C.nFeist, W. C. 1978b. Protecting wooden structures. Chemtech.8(3):160-162.nFeist, W. C. 1979. Protection of wood surfaces with chromium trioxide. USDA For. Serv. Res. Pap., FPL-339, For. Prod. Lab., Madison, WI.nFeist, W. C., and W. D. Ellis. 1978. Fixation of hexavalent chromium on wood surfaces. Wood Sci.11(2):76-81.nHart, J. R. 1981. Chelating agents in the pulp and paper industry. TAPPI64(3):43-44.nHayashi, A., and D. A. I. Goring. 1965. Studies on lignosulphonate (XVII). An investigation of the gelling reaction at lignosulfonate with dichromate. Pulp Paper Mag. Can.66(3):T154.nHon, D. N.-S. 1975. Formation of free radicals in photoirradiated cellulose. IV. Effect of ferric ions. J. Appl. Polym. Sci.19:2789-2797.nHon, D. N.-S. 1981. Photochemical degradation of lignocellulosic materials. Pages 229-281 in N. Grassie, ed., Development in polymer degradation—3. Applied Science Publishers, London, Chapter 8.nHon, D. N.-S. 1983. Weathering reactions and protection of wood surfaces. Paper presented at the Ninth Cellulose Conference, Syracuse, NY, May 24-27; Appl. Polymer Symposium, 37:845-864.nHon, D. N.-S., S.-T. Chang, and W. C. Feist. 1982. Participation of singlet oxygen in the photodegradation of wood surfaces. Wood Sci. Technol.16(3):193-201.nKringstad, K. 1969. Degradation of wood and high-yield pulps by light—A survey of the present state of knowledge. TAPPI52(6):1070-1074.nKubel, H., and A. Pizzi. 1981. Protection of wood surfaces with metallic oxides. Holzforsch. Holzverwert.33(1):11-14.nPizzi, A. 1979. Wood waterproofing and lignin cross-linking by means of chromium trioxide/guaiacyl units complexes. Holzforsch. Holzverwert.31(6):128-130.nPolcin, J., and W. H. Rapson. 1972. Sapwood and heartwood ground wood of Western hemlock and Jack pine. Part III. Influence of solvent extraction on the bleaching of pulps. Pulp Paper Mag. Can.73(1):86-92.nTanaka, H., and R. Senju. 1965. Paper presented at the Eighth Lignin Chemistry Symposium at Matse, Japan.nTarkow, H., C. F. Southerland, and R. M. Seborg. 1966. Surface characteristics of wood as they affect durability of finishes. Part I. Surface stabilization. USDA For. Serv. Res. Pap., FPL-57, For. Prod. Lab., Madison, WI.nWiles, D. M., and D. J. Carlsson. 1981. Stop photodegradation. Chemtech.11(3):158-161.n
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